1. Field of the Invention
This invention relates generally to apparatus for drying and storing grain within a grain bin, and more particularly to a rotating helical conveying system for moving the grain from a drying chamber to a storage chamber within the grain bin.
2. Description of Related Art
As discussed in U.S. Pat. No. 3,501,845, one type of apparatus which is used for drying grain comprises an inverted frusto-conical perforated drying floor mounted in a conventional grain bin above a base floor thereof. Raw grain is loaded onto the drying floor through an opening in the top of the grain bin and thereafter air dried by, for example, a blower system circulating air upwardly through the perforated drying floor. Once dry, the grain is dumped onto the base floor through discharge spouts in the drying floor controlled by trap door-type valves.
Another example of this type of grain drying apparatus is shown in U.S. Pat. No. 4,035,928, wherein the dried grain is unloaded from the drying floor 50 through openings 60 controlled by similar trap door-like valves 62 and 64. The '928 patent further discloses the use of a stiffening tube 23 secured to the underside of the grain drying floor to improve strength and support.
Still other examples of grain drying apparatus of the type to which the present invention relates are seen in U.S. Pat. No. 4,587,893 which discloses a tension band 28 extending around the lower circumference of the drying floor to improve the transmission of weight forces; U.S. Pat. No. 4,589,332 which discloses a flashing system 40 aimed at preventing the accumulation of grain at the juncture of the drying floor and the wall of the bin; and U.S. Pat. No. 3,943,636 which shows a hydraulic torque converter operatively connected to the drying floor discharge valves for moving the valves between open and closed positions.
One common problem associated with grain drying apparatus of this type is the general complexity of the mechanisms needed to operate the drying floor discharge outlet valves, which in some cases include numerous chains, levers, manual control rods or hydraulic cylinders in order to raise and lower the trap door-like valves controlling the discharge outlets. These types of mechanisms also make precise control over the amount of grain passing through the discharge outlets very difficult. Moreover, the problem of controlling the amount of grain discharged is often aggravated by trash or other debris becoming lodged in the discharge outlets of the type discussed above.